Switching system



March 2, 1937. c. A. COLLINS SWITCHING SYSTEM Filed Aug. 13, 1935 5Sheets-Sheet l g wgas nm S llll ATTORNEY C. A. COLL/NS ATTORNEV March 2,1937. A L' I 2,072,476

SWITCHING SYSTEM,

Filed Aug. 13. 1935 5 Sheets-Sheet 2 INVENTOR 3 CACOLLINS l ATTORNEYMarch 2; 1937.

C. A. COLLINS SWITCHING SYSTEM Filed Aug. 15, 1935 5 Sheets-Sheet 3I/WE/VTOR C. A. COLL INS 47' TORNEV c A. COLLINS SWITCHING SYSTEM FiledAug. 13, 1955 Ma ch 2, 1937. 2,072,476

5 Sheet s-Shee't 4 INVENTOR By CACOLL/NS Mai/ nd ATTORNEY March 2, 1937.c. A. COLLINS 2,072,476

SWITCHING SYSTEM Filed Aug. 13, 1935 5 Sheets-Sheet 5 RKS : I v I v 0 I,INVENTOR QACOLL/NS ATTOR/V V Patented Mar. 2, 1937 UNITED STATES PATENTOFFICE Application August 13, 1935, Serial No. 35,925

7 Claims.

10 to enable calls to be placed in a given group without blocking othercalls in the same group; and to otherwise improve systems of theforegoing character.

According to the invention these objects are attained by arranging aswitching mechanism,

comprising a field of circuit making contacts, in coordinate rows and bydividing the lines served by the switch in groups, each of which groupshas two appearances, one in a vertical row and one in a horizontal row,and providing means for selectively operating said contacts to extendcalls to said lines. By assigning a link to each Vertical row, a callmay be extended by any group of lines in its vertical-row appearancewithout decreasing the accessibility of any other group. Moreover, sinceeach group appears in a horizontal row of contacts, other calls may beextended by said group of lines in its horizontal-row appearance,provided there are links not engaged in calls from otherhorizontal-appearance groups.

Another feature is a switching mechanism in which the foregoingarrangement is applied to a cross-bar switch, the contacts of said linegroups in both their vertical-row and horizontalrow appearances beingoperated by the conjoint action of the bars of the same switchstructure.

These and other features of the invention will be more clearlyunderstood from the following detailed description, taken in connectionwith the accompanying drawings, and also from the appended claims.

In the accompanying drawings Fig. 5 shows the general plan of a systemembodying the invention, and Figs. 1 to 4, inclusive, when placedtogether as indicated in Fig. 6 illustrate the details of one method ofextending incoming calls to an idle one of a number of trunks leading toselector switches not shown.

The cross-bar switches shown in Figs. 2, 4 and 5 may be of anywell-known type such as the specific structure described in detail inthe pend ing application of J. N. Reynolds, Serial No. (702,453, filedDecember 15, 1933, granted as Patent 2,021,329, Nov. 19, 1935. While theinvention is shown a d d r b d in connection with cross-bar switches, itis not so limited in some of its broader aspects but may be embodiedinother kinds of switches, such as relay switches; also the invention isapplicable to other switching stages, such as intermediate and finalstages.

For the purpose of simplifying this description only one switch contactis shown at each crosspoint in the sleeve or control lead of each line,whereas the switch in actual practice would carry 3 or more contacts ateach cross-point, two contacts being required for the talking leadsshown at the top of Fig. 1 The arrangement of the switches is such thatany contact set is capable of operation upon conjoint displacement indefinite order of the two bars, illustrated in Fig. 5, which intersectin the locality of said set of contacts. The contact sets are maintainedactuated by the displacement of the last actuated one of the two bars,and they are restored to normal on the release of the last actuated bar.bar to be actuated in operating any given contact set is referred to asthe horizontal bar and is actuated by a selecting magnet shownimmediately to the left of each row of contact sets in each switch. Thesecond bar to be actuated is referred to as the vertical bar and isactuated by a holding magnet shown directly below the vertical row ofcontact sets in each switch unit.

Referring first to Fig. 5, the cross-bar switch arrangement is hereshown in schematic form in order to bring out more clearly the manner inwhich the subscriber lines are given access to incoming trunk circuits.The primary crossbar switch in the upper portion of this figure is thesame as shown in detail in Fig. 2 and provides each of thelOO subscriberlines with two multiple appearances arranged in such a way that eachsubgroup of 10 successive lines appears in a vertical row in the firsthalf of the switch with direct access over a particular link to any oneof the incoming trunks and in a horizontal row in the second half of theswitch where the lines have access over diiferent links to any one ofthe incoming trunks multipled horizontally in the secondary cross-barswitch located in the lower portion of this figure. Arranging the linemultiple in this manner provides a high degree of trunk accessibility,considering the number of line appearances, because in any subgroup of10 lines one link circuit is available for reaching any one of theincoming trunks. If said trunk is busy, then each line has a link overwhich the call may reach an incoming trunk. Thus if 10 incoming callsshould be centered in one subgroup of 10 lines, all 10 calls will haveaccess to the incoming trunks over separate links and no call will beblocked unless a link is engaged on a call to some other horizontalappearance group.

Referring now to the drawings comprising Figs. 1 to 4, they show bymeans of the usual circuit diagrams a sufficient amount of the equipmentin an automatic telephone exchange system embodying the features of theinvention to enable the invention to be understood. Fig. 1 shows typicalline and cut-01f relays arranged to represent a group of 100 lines inwhich the first vertical row of relays represents lines I to I0. Thesecond vertical row represents lines I I to 20, and a third rowrepresents lines 9| to I00, with only the multiple indicated for theintermediate relays. Also a group of control relays such as AI, BI, andDI are shown at the extreme right of each of the 10 horizontal rows ofline relays. These relays in conjunction with another group of controlrelays such as CI of Fig. 3, corresponding with each vertical row ofline and cut-off relays, identify the number of the line that is callingso that the trunk to which the line has access may be tested for busy,as will later be described. The control relays referred to above arefurther controlled or directed by relays 30I, 302, 303, 304, and 305located in the upper right corner of Fig. 3 and prevent more than oneline at a time from being assigned to an idle trunk as well as directthe selection of the trunk. The system also includes two cross-barswitches, shown in Figs. 2, 4 and 5, arranged as primary and secondaryswitches with 20 links running vertically and connecting with 10 trunksrunning horizontally. The vertical row of the TKI etc. relays to theleft of Fig. 4 act as busy test relays, causing the call being connectedover one of the vertical links to be directed to the first idle trunk ofthe incoming trunk group.

A detailed description will now be given of the manner in which anincoming call may reach any idle trunk over a particular link circuit orif said link is busy, the manner in which the call may reach any idletrunk over a different link circuit. When the usual receiver is removedat a subscribers station, such as SI, a bridge is placed across the lineconductors IN and I02 of Fig. 1. This causes line relay LI to operate,ground being connected to lead I02 at outside right break contact ofcut-01f relay COI and battery through winding relay LI is connected tolead [M at inside break contact of relay COI. Upon operating, relay LIat its right inner contact prepares a path for operating relay CI byconnecting lead I04 to lead I05 as later will be described. Relay LIalso closes a circuit for operating relay AI over a path traced fromground on lead I06, right outer contact relay LI, lead II, top breakcontact relay DI to battery through winding relay AI. Relay AI at itsfront contact I08 connects lead I09 to left winding relay BI. Lead I09being a test lead running through the armatures and back contacts onother relays A2 to AIO will be open at the left back contact relay 303if another call in the group of lines is already in the process ofselecting a trunk. Assuming, however, that relay 303 is not operated,then ground from the break contacts of relays 30I and 302 will beconnected through break contact relay 303, lead I09, through the breakcontact of relays All] to A2 make contact on relay AI and through leftwinding relay BI to battery. Had it been assumed that simultaneous callshad originated on subscriber lines I and 2 or on lines I and I0 thenrelays B2 or BIO, respectively, would have operated in the pathpreviously traced, in preference to relay BI. Since a call from line Iis being traced, relay BI operates to close a circuit from batterythrough the right winding relay BI and front contact to another testlead I I0 through the armatures and break contacts on other B relays toground through winding relay 303. Relay 303 operating, then opens leadI09 as mentioned above and prevents later calls from interfering withthe handling of the call on line I. Test leads I09 and H0 thereforecontrol the vertical preference and permit the lowest of the callinglines in any group of 10 to search for a trunk and lock out all otherlines until an idle trunk is found or'until the call is timed out whenanother attempt will be made to select a trunk.

Before a search is made for an idle trunk for the call on line I, it isnecessary to find out in which vertical group of 10 lines the callingline is located, otherwise referred to as the horizontal preference.This is determined by the common relay 304 in upper right corner of Fig.3 and the relays CI to CIO inclusive, together with lead 300. Therefore,immediately after the vertical preference is determined, described inthe preceding paragraph, the BI relay closes a circuit for operatingrelay CI of Fig. 3 over a path traced from ground at the top breakcontact relays 30! and 302, through armature and back contact relay 304,thence over multiple lead 301, contact I I on relay BI, multiple leadI05, through operated inner contact on relay LI, multiple lead I04, andthrough bottom winding relay CI to battery. Relay CI in operating, locksto ground through its upper winding and front contact to lead 300,traced through all the top break contacts and armatures of relays C2 toCIO, thence through winding of relay 304 to ground at break contacts ofrelays 30I and 302. Relay 304 in operating opens its own top contactwhich breaks the operating circuit previously traced for the lowerwinding of relay CI, thus preventing later calls that might originate inother groups of lines from interfering with the handling of the call online I. The identity or location of the calling line is thus establishedby virtue of the fact that only one of the B and one of the C relays,namely Bi and CI, remain operated. Before proceeding to show how thisline is actually connected with an idle one of the incoming trunks, itis thought that this vertical and horizontal preference will be moreclearly understood if a description is given of several other caseswhere more than one line originates a call at the same time.

Assuming for example that subscribers SI and SH lift their receiversabout the same time, line relay LI and corresponding BI and CI relaysoperate as previously described. Line relay LII also operating connectsground that is lead II 2 to lead I01. Since both relays LI and LIIconnect ground to lead I01, which path is further traced through relayAI, it is evident that only the BI relay will operate. The verticalpreference is thus determined by the BI relay being operated, both linesbeing the topmost one in their respective subgroups. When, therefore,ground is placed on lead I05 at contact III by relay BI, a circuit isestablished for operating both the CI and C2 relays, traced over leadI05 to right inner contact relay LI I and lead I I3 to battery throughlower winding relay C2; also traced over lead I05 through inner contactrelay LI, lead I04, to battery through lower winding relay CI. In thiscase the locking circuit through the upper winding relay C2 is completedback over the series lead 306 to the winding of relay 304 to ground,while the locking circuit through the upper winding of relay Cl is heldopen at contact 308 on relay C2. Relay 304 operating thus opens at itstop break contact the circuit for energizing the lower windings ofrelays CI and C2, so that relay CI releases and relay C2 remainsoperated. In this manner, line II is identified as the calling line tobe handled first, and search for an idle incoming trunk will be directedby the combination of the BI and C2 relays remaining operated, as willlater be described.

Another example is assumed where subscribers SI, SI I and SI 09 lifttheir receivers nearly simultaneously, in which case relay AI operatesover lead I01 through contacts on relays LI and LII as previouslytraced. Line relay LI00 also operating connects ground that is on leadII4 to lead I I 5, thence through top contact and armature on relay DIOthrough winding relay AIO to battery. The operation of relay AIO causesrelay BIO to operate from ground on lead I09, and at the same time theright break contact of relay AIO opens the circuit to the armature relayAI and prevents relay BI from operating. The failure of relay BI toconnect ground to lead I05 prevents relay CI and C2 from operating. Onthe other hand, relay BIO at contact H6 connects ground to lead III foroperating relay CIO, further traced through inner contact relay LI00,lead I I8, to battery through lower winding relay CIO. In this mannerline I00 is identified as the calling line to be handled first andsearch for an idle incoming trunk is determined by the combination ofthe BIO andCIO relays remaining operated, as will later be described.

Going back to the condition ensuing forthwith upon the identity ofcalling line I being determined by relay BI the relay CI remaining in anoperated condition, there will now be described the manner in which asearch is made for an idle trunk. Relays 303 and 304 of Fig. 3 it willbe remembered are also in an operated condition at this time, whichprevents interference from other lines that might originate calls. Sinceeach calling line has two possible link paths for selecting an idletrunk, it will be assumed that the first choice path is available. Saidpath includes link 20I and anyone of the trunks 40I to M0. It is furtherassumed that trunk M0 is idle. Relay LKI of Fig. 3 and relay 'IK ID ofFig. 4 therefore are normal, because if the above link and trunk werebusy these relays would be in an operated condition as will presentlyappear. The circuits of this system are organized for positive operationby preventing the holding magnet circuit of the cross-bar switches frombeing closed until the selecting magnet of both the primary andsecondary cross-bar switches have operated. The circuit for selectingmagnet 22I of the primary switch of Fig. 2 may be traced from ground onbreak contacts of relays 30I and 302, to armature and front contact onrelay 303 to multiple lead 309, thence through contact II9 on relay BI,lead I20, through contact 3I0 on relay 3 which is operated at this time,armature 3I2 on relay LKI and back contact over lead 3 I 4 throughWinding of selecting magnet 22I to battery. In the path just traced,relay 3I I is operated because the horizontal preference relay CIconnects ground at contact 3 I 5, thence to battery through windingrelay 3. Selecting magnet 22I when it operates prepares a path at itsbottom contact for operating relay DI of Fig. 1 as will later bedescribed. It also connects ground at contact 22 to lead 223 foroperating one of the selecting magnets of the secondary cross-barswitches of Fig. 4, dependent on the associated incoming trunk beingidle. Trunk M0 in this case being assumed to be idle,.lead 223 mayfurther be traced through the armature and back contact of relay TKIDtobattery through selecting magnet II I.

The operation of selecting magnet 4II connects ground to lead M2 forcausing the holding magnets HI associated with link 20I to operate.Ground on lead 4I2 thus may further be traced to the bottom contact ofselecting magnet 22!, lead 224 through winding relay DI to battery.Relay DI operating, at its top break contact, opens the circuit of slowreleasing relay AI, causing it to restore to normal. The slow releasefeature delays its release long enough to insure the operation of relay305. At contact I20 relay DI prepares a locking circuit for itselftraced to multiple lead I2I toground at left inner contact relays Al toAIO, as will later be explained. At contact I22 relay DI closes atemporary path from ground at contact I23 on relay Al to lead I24, tobattery through winding relay 305. Relay 305 operated closes a lockingcircuit for itself through its own contact 3I6 toground at back contactson relays 30I and 302. Relay 305 at contact 3I'I connects ground tolower front contact relay 304, thence to lead 3I8 for operating timingrelays 30I and 302 and operating relay 3I9 through contact 320 on relayCI to prepare the 10 leads indicated at 32I for operating one of theholding magnets. Although relay 3I9 closes the circuit for ten holdingmagnet control leads, only one lead will have ground connected to itdepending on which one of the BI to BIO relays is operated. Since thecall on line I involves the operation of relay DI, as previouslydescribed, the circuit for operating holding magnet HI of the secondaryswitch of Fig. 4 may be traced from ground through operated make contacton relay 303, multiple lead 309, contact I25 on relay BI over lead I20,through contact 322 on operated relay 3I9, thence through armature 323,relay LKI and back contact over lead 324 to the mid-point of the twowindings on holding magnet HI of Fig. 4 and through the right-handwinding to battery. The holding magnet operating in this circuit extendsthe link 20I to the trunk 4I0 through cross-bar switch contacts 4I3.This holding magnet is also equipped with a make contact which at thistime connects ground to lead M4 for operating the holding magnet HI ofFig. 2 to battery, thus extending line I to the link 20I through theprimary cross-bar switch contacts 225.

In the system of this invention upon connecting with an idle trunk,ground is returned over the sleeve or control lead for holding theconnecting switches until the subscriber restores his receiver to theswitchhook all in a manner well understood in the art. Therefore, soonafter calling line I is extended to incoming trunk 4I0, ground may betraced from the trunk sleeve II5 through contacts 4I3, lead 4I6 throughwinding of relay LKI, lead 325, and left winding holding magnet HI ofFig. 4 to the mid-point of the magnet windings to which direct operatingground was traced in the previous paragraph. Thus when the timing relays30I and 302 operate as described below and remove ground from the leadconnected to the mid-point of the holding magnet Winding, the magnetcontinues to remain operated on the trunk holding ground through bothwindings in series. Furthermore, since the winding of relay LKI isincluded in the path just traced, relay LKI also operates and remainsoperated as long as the connection is held by the subscriber, therebytransferring the trunk selecting circuits to a second set of linkcircuits. At this time cut-off relay COI also operates from ground ontrunk sleeve 4I5, over link sleeve 20I, switch contacts 225, and leads226 and I03 to battery through winding relay COI. Relay COI operatingreleases relay LI, this action taking place before the timing relays 30|and 302 function.

Referring again to the locking circuit for relay DI to ground on leadI2I, this feature provides a more uniform distribution of trunks tocalling lines by permitting only one call at a time in a givenhorizontal row of lines to select an incoming trunk. That is, if someother relay such as A2 is operated when relay DI comes to release, thenground placed on lead |2I by relay A2 prevents relay DI from releasingand thereby at its top break contact holds lead I! open, thus preventingthe reoperation of relay AI. Therefore with any abnormal number of linescalling, the effect of this feature is to allow one call to be assigneda trunk in each of the ten groups of lines before a second call in anygroup may be assigned a trunk.

As described above, relay 305 connects ground to lead 3|8 for operatingthe cross-bar switch holding magnets which thus completes the connectionof the line to an idle incoming trunk. Timing relays 30I and 302therefore measure off sufficient time for completing the connection.Relay 302 being slow to operate permits the holding magnets to beoperated before it disconnects ground from the hold magnet operatingpath traced over lead 309 etc. Relay 302 fully operated causes relay 305to release and in turn the slow relay 30I. The latter is sufficientlyslow in releasing to allow the LK relay, associated with the link justmade busy on the last call, to operate and prepare the system forreceiving another call.

Having described the call from subscriber S! on the assumption that thelink I was idle, the call will now be traced on the assumption that link20! is busy and that the next link path is available. In this case itwill be observed that the second choice appearance of line SI is in theright hand portion of the primary cross-bar switch of Fig. 2, and toreach an idle trunk it must be assumed that the link 2| I is idle, whichmeans that all cross-bar switch contacts associated with this link areopen and that the holding magnets HI I are unoperated. It will beremembered that removal of the subscribers receiver caused the BI relayof Fig. 1 and the CI relay of Fig. 3 to operate and mark the location ofthe calling line. These relays together with relays 303 and 304 remainoperated until the line is connected to a trunk. When relay 303 firstoperated, ground was connected to lead 309 for operating selectingmagnet 22| over the 'same path as before, due to both appearances ofline SI being served by the same selecting magnet. Operating selectingmagnet 22I of Fig. 2 at its lower contact prepares a path for operatingrelay DI of Fig. 1 and at contact 222 closes a ground to multiple lead223 which extends through a series circuit running through the righthand armatures and front and back contacts of the 10 test relaysassociated with the 10 incoming trunks 40I to 4I0. Lead 223 connectsfirst to the armature of relay TKIO but if the associated trunk M0 isbusy, ground on the sleeve lead 4| 5 operates relay TK|0 and lead 223 isthereby extended to the right armature of the next relay TK9, not shown.For purposes of this description it will be assumed that trunks 403 toMD are busy and that trunk 402 is idle. Lead 223 is thus extended to theright armature of relay TK2, thence over the back contact to batterythrough selecting magnet 4!! associated with trunk 402. Selecting magnet4|! operating connects ground to multiple lead 4I2, further tracedthrough bottom make contact on operated selecting magnet 22|, thenceover lead 224 to battery through winding relay DI. The latter relay aspreviously described supplies ground at contact I22 to lead I24 foroperating 305 which starts the holding magnet selection.

Relay 305 operating, closes a ground circuit at contact 3!! throughlower contact and armature relay 304 to lead 3I8 for operating relay 3I9which closes the I0 holding magnet leads indicated at 32 I. Aspreviously described the ground connected to lead 309 at relay 303 isfurther traced through contact I25 on relay BI, lead I26, contact 322 onrelay 3|9, armature 323 on relay LKI and front contact to lead 326,thence through armature and back contact slow operate relay LKI to themid-point of holding magnet HII of secondary cross-bar switch of Fig. 4.The holding magnet operating to battery through its right hand windingconnects ground to lead M8 for operating the holding magnet HII of theprimary cross-bar switch of Fig. 2 and at contacts 4|9 extends the link2 to the incoming trunk 402. The operation of the holding magnet atcontact 22! extends the calling line I to the link 2I| thus completingthe connection of this line to incoming trunk 402. Relay LKII referredto in the above circuit acts as a busy relay by opening lead 326 andpreventing interference when the link 2|! is engaged. According to theusual operation ground is returned by the incoming trunk over sleevelead 420, link 2 I I, through winding relay LKII, and left windingholding magnet HII before ground is removed from lead 326 by the slowoperate control relay 302 of Fig. 3. Relay LKII therefore cannot operateuntil this ground path is opened by the operation of relay 302. Theholding magnet I-III continues to be held by a circuit through its twowindings and winding relay LKII in series back tothe incoming trunkholding ground. Relay LKII being operated prevents this ground frombacking up over lead 326 and prevents interference with another callthat might try to select the same link.

Let it be assumed now that both subscribers SI and SI! attempt tooriginate a call at the same time. As previously described, only lineSII will be identified by the control relays of Figs. 1 and 3 whereinrelays BI and C2 remain operated until a connection is established. Thisline, as in the case of line I has two different links over which it mayreach any idle one of the incoming trunks, so that for the purpose ofthis description one path only need be traced which will be assumed tobe the one over the first choice link in which the multiple of line IIappears in the left-hand half of the switch of Fig. 2. The associatedlink 202 under this assumption being idle at this time means that testrelay LK2 and holding magnets H2 are unoperated. Relay C2 being operatedconnects ground at contact 32'! for operating relay 328 which prepares apath for all ten selecting magnets of the primary switch of Fig. 2.Relay Bi being operated connects ground at contact H9 to lead I20 andthrough contact 329 on relay 328 for operating selecting magnet 221traced over armature 339 of relay LK2 and back contact over multiplelead 3 and through winding of selecting magnet 22! to battery. Theselecting magnet operating closes ground at contact 222 to multiple lead223 for selecting an idle incoming trunk, assumed in this example to betrunk 4l0. Ground on lead 223 is thus further traced through armatureand back contact relay TKIO to battery through selecting magnet 4 of thesecondary switch in Fig. 4. Operation of this magnet connects ground tolead M2 for operating relay Di and common relay 305 as previouslydescribed, which in turn connects ground to lead 3! for operating theswitching relay 33| through contact 332 on relay C2. Relay 33l closesthe circuits of all associated holding magnets so that ground connectedby relay Bl at contact I25 to lead I26 may then be further tracedthrough contact 333 on relay 331, armature 334 on relay LKZ and backcontact over lead 335 to mid-point of windings on holding magnet H2 ofFig. 4, thence through the right hand winding to battery. Line llappearing in the left hand side of the switch of Fig. 2 is thereforeconnected to link 202 which in turn at contact 42! is connected toincoming trunk 4H] similar to the manner in which line I was previouslyconnected.

If as previously discussed subscribers SI, SH and SI 00 originate callssimultaneously, then the control relays of Figs. 1 and 3 will identifyline I00 as the line next to be served and relays BIG and C l I] willremain operated until the connection is completed. Relay CIIJ causes theoperation of relay 336 which closes the selecting'magnet leads indicatedat 331 and relay 338 which closes the holding magnet leads indicated at339. These leads all connect with the armatures of relay LKH) so that ifthe link 2I0 is idle the selecting magnet leads over the back contactswill each connect with the corresponding selecting magnets on theprimary switch and the holding magnet leads will connect with the onelead 340 leading to holding magnet Hi0. Then the particular Bl etc.relay will determine which one of the ten selecting magnets is to beenergized. In this example, relay BIO remains energized, therefore,selecting magnet 228 will be energized. The latter magnet connectsground to lead 223, causing one of the secondary switch selectingmagnets to operate corresponding to the first trunk that is idle. If allexcept trunk 4M are assumed to be busy then ground on lead 223 operatesselecting magnet 422 which connects ground to lea-d 4 I 2 for operatingthe holding magnet Hi0 similar to that described in the case of line I.Line I00 appearing in the primary switch of Fig. 2 is therefore extendedthrough contacts 229, link 2), contacts 423 of secondary switch andthence to incoming trunk 40!.

What is claimed is:

1. In combination, a group of lines, a switch having coordinate rows ofseparately operable contact sets, the lines of said group beingconnected respectively with individual contacts in a row in onecoordinate direction and also connected respectively to individualcontacts in a row in the other coordinate direction, and means forselectively operating said contacts.

2. In combination, a switch having vertical and horizontal rows ofseparately operable contact sets, circuits appearing respectively insaid vertical rows of contact sets, and groups of lines appearingrespectively in said vertical rows of contact sets and appearingrespectively in said horizontal rows of contact sets.

3. In combination, a cross-bar switch having a field of contactsarranged in vertical and horizontal rows, groups of lines, said groupsappearing respectively in vertical rows in one portion of said contactfield and in horizontal rows in another portion of said contact field,and means for selectively operating said contacts.

4. In combination, an automatic switch having a plurality of separatelyoperable cont-act sets arranged in vertical and horizontal rows,operating bars individual respectively to the vertical rows, coordinateoperating bars individual respectively to the horizontal rows, a groupof lines appearing in the contact sets of a vertical row and alsoappearing in the contact sets of a horizontal row, telephone circuitsconnectable to said lines either through the contacts of the verticalrow or through the contacts of the horizontal row in which said linesappear, and means controlled by the conjoint operation of two of saidbars to selectively operate any desired set of contacts.

5. In combination, an automatic switch having a plurality of separatelyoperable contact sets arranged in vertical and horizontal rows, verticalbars individual respectively to said vertical rows, horizontal barsindividual respectively to said horizontal rows, groups of linesappearing in the respective vertical rows and also multiplied to appearin the respective horizontal rows, telephone circuits, means foroperating one pair of bars to connect a particular line to one of saidtelephone circuits by actuating the corresponding set of contacts of thevertical row in which said line appears, and means for operating anotherpair of bars to connect said line to one of said tele phone circuits byactuating the corresponding set of contacts of the horizontal row inwhich said line appears.

6. In combination, an automatic switch having a plurality of separatelyoperable contact sets arranged in vertical and horizontal rows, verticalbars individual respectively to said vertical rows, horizontal barsindividual respectively to said horizontal rows, a group of linesappearing in a particular one of said vertical rows and also appearingin a particular one of said horizontal rows, a link appearing in allcontact sets of said particular vertical row, a second link having asingle appearance in each of said horizontal rows of contacts, meanseffective if said first link is idle for operating a pair of barsto'connect a line of said group to said. first link through thecorresponding contact set in said vertical row, and means effective ifsaid first link is busy for operating a second pair of bars to connectsaid line to said second link through the corresponding contact set insaid particular horizontal row.

7. The combination with a group of lines of a switch having coordinaterows of separately operable contact sets, the lines of said group beingconnected respectively to individual contacts in a row in one coordinatedirection and multipled to appear respectively in individual contacts ina row in the other coordinate direction, and means for selectivelyoperating said contacts.

CYRIL A. COLLINS.

